Visualizing and comparing teacher's mathematical prctice

The research problem addressed in this paper is the visualization of the essential elements of the mathematical activity arising during classroom practice (definitions, properties, mathematical processes, etc.). We provide a tool for this purpose that displays these elements in the form of a graphic, and apply it to the study of the commonalities and differences in three different classes by diffe-rent teachers in the same institution, year and school level when they teach the bisector. The results permit to infer further aspects of mathematical knowledge in the teaching practice.